Electrical heating panel



Feb. 6, 1951 .1. F. SCHREIBER ELECTRICAL HEATING PANEL 2 Sheets-Sheet 1 Filed Oct. 25, 1947 INVENTOR. Jay/V ff JC/l/Ff/JZK "lbob amen A I TORNE Y Feb. 6, 1951 J. F. SCHREIBER ELECTRICAL HEATING PANEL 2 Sheets-Sheet 2 Filed Oct. 25. 1947 Patented Feb. 6, 1951 UNITED STATES PATENT OFFICE ELECTRICAL HEATING PANEL Application October 25, 1947, Serial No. 782,096

2 Claims. 1

This invention relates to electrically heated building panels adapted for installation in the ceiling and, if desired, walls of a room of a building to supply such room with radiant heat.

The electrically heated panels contemplated by the present invention are so constructed that they may be nailed directly to the stringers or other frame Work of the room to thereby become a permanent part of the ceiling or walls of the room, so that when the room is finished by plastering or papering the ceiling and walls thereof, the heating panels will be completely concealed and as a result the room can be heated without any visible signs of the means that supply the heat.

The use of the electrical heating panels contemplated by the present invention makes the problem of heating a house extremely simple, since no heating stove, furnace or chimney is needed and no portion of the interior of the room is obstructed by a radiator or other heating apparatus. Furthermore these heating panels are preferably so positioned in the ceiling, or, if desired, walls of the room as to give uniform distribution of the radiant heat, so that the room will be free from the drafts and objectionable air currents ascribable to certain other heating systems, and the temperature of the room will be approximately the same for all portions thereof. Also when a room is heated with radiant heat emitted from the ceiling the floor will receive an added amount of heat due to the heat rays striking the floor.

It has been common practice for years to cover the supporting beams for the walls and ceiling of a room with thick sheet material such as building board, Wall boards, plaster-boards, insulating sheet rock etc. The electrically heated panels contemplated by the present invention are so constructed that they may be nailed to the supporting beams or stringers of a room as a permanent structure, like ordinary Wall board. The entire ceiling may be made up of electrical heating panels constructed in accordance with the present invention, or only portions of the ceiling may be formed of these panels, which are disposed as required to provide the desired amount and distribution of heat. The rest of the ceiling may be made up of ordinary wall board, whereupon the entire ceiling may be papered as usual or covered with plaster to conceal the electrical heating panels of the present invention.

In order to provide an electrical heating panel which is sumciently durable to give satisfactory service for many years, and which will maintain its shape and not sag or warp or present a fire hazard, it is important that such heating panel shall consist largely of a fire-resistant building board capable of giving good service, and for this purpose I prefer to use a commercial type of building board formed of a mixture of asbestos fibers and Portland or hydraulic cement. Each face of this asbestos-cement board is preferably covered with a durable insulating sheet such as a sheet of paper or woven fabric impregnated with a thermosetting resin such as phenol formal-- dehyde.

To one face of the building board which has been covered with an insulating sheet such as just described, is applied a special type of heating unit consisting of a sheet of paper or woven fabric having applied to one or both faces thereof a rubber composition or plastic composition containing conductive carbon particles that serve to render the sheet conductive throughout its area. In order to provide this conductive sheet with operating current a flat conductor strip is provided along two of the four edges of the con ductive sheet, so that when a difference in electrical potential is maintained between these two strips the conductive sheet will generate heat, but at a relatively low temperature in the range of F. to F.

This conductive sheet is then covered with one or more layers of insulating material such as the insulating sheets above mentioned. In heating a room from the ceiling the electrical heating panels are so positioned that the heating sheet just described will face downwardly so that the radiant heat it produces will be directed down- Wardly into the interior of the room. However some heat will pass upwardly through the supporting building board above described to escape upwardly above the ceiling of the room. This loss of heat may be reduced in accordance with the present invention by employing a sheet of aluminum foil or other material of low emissivity which is applied to the upper face of the panel to reduce the amount of radiant energy that would otherwise escape in an upward direction.

The several insulation sheets above mentioned are all preferably treated with a durable thermosetting resin, and the various parts of the panel are assembled before such resin is set, whereupon the assembled parts of the panel are placed in a platen press to cure the resin under heat and pressure so that the various plies may be firmly bonded to each other and to the wall board and thereby form an integral heatin panel.

The primary objects of the present invention are; to provide a house heating means which is simple and inexpensive in construction and is easy to install; which is capable of heatin each room of a house to the desired temperature without forming drafts or objectionable air currents; which takes up no space in a room and is completely concealed from sight; and which comprises a heat source of large area and low temperature.

The above and other features of the present invention will be further understood from the following description when read in connection with the accompanying drawings, wherein:

Fig. l is a perspective view with parts broken away of an electrical heating panel constructed in accordance with the present invention, and showing the back of the panel which is covered with metal foil.

Fig. 2 is a similar view with parts broken away and looking at the front of the panel or face from which the heat radiates.

Fig. 3 on an enlarged scale is a sectional View taken on the lines of t of Fig. 1.

Fig. 4 is a similar view taken on the lines ld of Fig. 1.

Fig. 5 is a perspective view somewhat similar to Fig. 2 but shows the various plies as partly 4 rolled back from the building board sheet; and

Fig. 6 is a plan View of the ceiling of a room equipped with heating panels of the present invention to heat the room, the ceiling being viewed from below.

The electrically heated building panel contemplated by the present invention should be sufficiently strong and durable to give years of satisfactory service when installed in the ceiling or walls of a room as a permanent part of the ceiling or wall structure. The panel is therefore preferably formed largely of a sheet of building board it, and while such sheet may be formed of any one of a number of building board materials now on the market, it is preferred to use a commercial type of building board formed of a mixture of asbestos fibers and Portland or hydraulic cement, because such board is fire-resistant and is not likely to bulge, warp or get out of shape.

Both faces of this building board ill are preferably covered with durable electrically insulating material such as paper or woven fabric impregnated with a durable thermo-setting resin. The building board It] is shown as having one face thereof completely covered with the insulating sheet H and the other face thereof completely covered with a similar insulating sheet i2. These sheets H and 32 are preferably impregnated with such resin as phenol formaldehyde laminating varnish.

When the electrically heated panel herein contemplated is installed upon the ceiling of a room one surface will necessarily face upwardly away from the interior of the room and the other surface will face downwardly towards the interior of the room. That surface which faces upwardly away from the interior of the room and herein called the back is, in accordance with the present invention, covered with a bright surface of low emissivity, such, for example as aluminum foil It which appreciably reduces the radiation loss from the back of the panel, increases the operating temperature of the panel for a given input, and causes a preponderance of the radiated portion of the panels output to be directed downwardly into the room. The word emissivity has a definite and well understood meaning and may be defined as the ratio of the time rate of energy loss by radiation from unit area of a surface to the time rate of energy loss by radiation from a unit area of a black body at the same temperature, the black body being one which is totally absorptive of radiant energy impinging upon it. The sheet metal foil 53 is shown as lying in direct contact with the insulating sheet ll. It can be formed of various non-corroding metals having a bright surface or of sprayed metal particles.

In order to render the panel so far described effective as a source of radiant heat, the lower face of the board It which carries the insulating sheet I2 is completely covered, except for its marginal edge portions, with a heating sheet i l which comprises a sheet of paper or woven fabric having applied thereto one or more layers of a thin solvent rubber or resinous material carrying conductive carbon particles such for example as acetylene black, to thereby impart to this sheet the desired amount of conductivity throughout its area. The sheet l4 may be broadly described as comprising a carrier sheet having deposited thereupon a plastic binder of resin, rubber or rubber-like material containing conductive particles, and for a specific example of such a conductive sheet attention is called to the Bull et al. Patent No. 2,314,766. The sheet it, it should be noted, is somewhat smaller in area than the board it to thereby leave a marginal edge entirely around the panel which is free from the heating sheet M, so that nails may be driven through this marginal portion of the panel into the wooden beams or other supporting structure of the room, without piercing the heating sheet.

To provide the heating sheet with oper ating electric energy this sheet has secured to one marginal edge thereof the flat conductor strip or tape it which is bonded directly to the sheet l fthroughout its length in a special maner, to be described, so as to form a good elect 'ical connection between the sheet i i and strip The opposite marginal edge of the sheet i i secured thereto a similar conductor strip iii. two strips are. preferably made of thin metal such as sheet aluminum, and the rip it is shown as having at one end thereof e laterally extending conductor l'i' which exonds across the board it in spaced relation to the conductor sheet i l and terminates near one end of the strip it.

It is important that the strips and i6 be bonded to the sheet l l so as to provide good elec trical contact therebetween and, therefore each of these strips has applied to the face that is to engage the sheet i l a mixture of phenol formaldehyde and vinyl resin carrying acetylene black, to bond the strip and sheet together without f rming an insulator therebetween.

The electrical heating sheet It should, for

5 safetypurposes, be well insulated from external objects and is therefore shown as covered with the two insulating sheets l8 and 19 which may be constructedthe same as the insulating sheets i! and 12. To the outer face of the sheet I9 is preferably applied a covering sheet such as ordinary woven fabric or paper, so that when 'theroonrin which this panel is'installed is finished the fabric 20 may be covered with wall paper, ormay be otherwise finished with the rest of the room. In some cases itmay be desirable to provide the lower face of the panel covered with the sheet with a high gloss finish by treating the same with a durable glossy resin such as a melamine resin.

Since, as above stated, the heating sheet 14 does not extend to the outer edges of the building board it, the thickness of the ply construction so far described will be slightly reduced beyond the edges of the heating sheet I 4. It may therefore be desirable to lay a filler strip 2% which may be formed of the same material as the insulating sheet H in this space around the heating sheet, to thereby provide an electrical heating panel of uniform thickness throughout.

In order to cause the sheet [4 to produce radiant it is necessary to supply the conductor strips i5 and It with electric energy, and to this end the strip 15 is connected to a conductor post 22, and the strip H is connected to a similar post 23. These posts are mounted in holes in the board it and preferably are so constructed that they will not project from either face of he heating panel. The post 22 passes through a hole formed in the sheet !2 and strip i5 and has a head 24 that clamps these parts within a recess formed in the board l5 as shown. The post 23 passes through a hole in the sheet [2 and strip 5? and has a head 25 that clamps this strip in a recess in the board l9.

After the parts have been assembled as described and with the various resin impregnated sheets carrying resin which is in an unset condition, this heating panel is placed in a platen press so that it may be subjected to heat and pressure for a sufficient length of time to set the resinous material carried by the different layers and thereby bond the portions of the panel firmly together to form an integral, water resistant, electrically heated building panel ready for installation in a building for use to supply a room with radiant heat.

This electrical heating panel may be made up in any convenient size. Panels four feet square are considered a good practical size for installation in a building where they can be nailed directly in the usual ceiling supporting stringers or wall beams.

The room ceiling shown in Fig. 6 of the drawing is illustrated as made up of 12 panels all of the same size and shape. Six of these are electrically heated panels marked H and constructed in accordance with the present invention. The other six are non-heated panels constructed of any suitable wall board or building board material, but they preferably have the same thickness as the heated panels. After the heated and non-heated panels have been nailed in place against the stringers 23, the cracks 2? between the panels are covered with adhesive strips, not shown, whereupon the entire ceiling may be plastered like any ordinary ceiling or it may be covered with wall paper such as indicated by 28.

In order to supply operating current to the electrically heated panels, a threaded post 29 is 6 screwed into each of the internally threaded posts 22 and 23, and each post 29 has a collar 30 and clamping nut 3| adapted to be screwed into clamping engagement with a current supply wire.

The electrically heated panels are shown in Fig. 6 as distributed upon the ceiling so as to heat the entire room practically uniformly, and one method of wiring these panels consists of the current supply wires 32 and 33 which may lead from a source of energy to a thermostat control box 34 mounted upon a wall of the room to be heated. This box is connected by the wires 35 and 36 to the various panel posts 29, and the two posts 29 for each panel may be enclosed in at protecting box 31. The wires 35 and 36 which are located above the ceiling may be installed and connected to the posts 29 after the ceiling panels are put up, provided a workman can crawl along the stringers 26 above the ceiling.

Each panel of the present invention is a self contained heating unit ready to be installed, and each room of a house provided with the heating panels of the present invention is preferably provided with a thermostat 34 or ordinary electric switch for turning the heating current on or off. The operating current supplied to a panel should not heat the panel to more than about F. in order to secure a long service from the panel and avoid fire hazards.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. An electrically heated building panel for installation as part of the ceiling of a room to supply the room with radiant heat, comprising a firercsistant building board containing asbestos fibers and having a resin treated sheet of fibrous material firmly bonded to each face of the board, a bright surface sheet of low emissivity adhesively bonded to one of said fibrous sheets to cover the face of the board that faces upwardly away from the interior of the room to reduce radiation loss, a heating unit adhesively bonded to the other resin treated sheet and including a fibrous sheet carrying a plastic binder containing carbon particles that render the sheet conductive throughout its area, flat conductor strips secured along two opposite edge of the conductive sheet and each strip being bonded to the conductive sheet by a resin adhesive containing conductive particles that form a conductive path between the strip and sheet so that current will be conducted across across the area of the sheet when these strips are at a different electric potential, an insulating sheet covering said heating unit, and all sheets being firmly bonded to the building board to form an integral heating panel.

2. An electrically heated building panel for installation as part of the ceiling of a room to supply the room with radiant heat, comprising a fireresistant building board containing asbestos fibers and having a resin treated sheet of fibrous material firmly bonded to a face of the board, a heating unit adhesively bonded to the resin treated sheet and including a woven textile sheet carrying a plastic binder containing carbon particles that render the sheet conductive throughout its area, fiat metal conductor tapes secured along two opposite edges of the conductive sheet and each tape being bonded to the conductive sheet by a resin adhesive containing conductive particles that form a conductive path between the tape and conductive sheet so that current will be conducted across the area of the sheet when these tapes are at a different electric potential, an insulating sheet covering said heating unit,

and all sheets being firmly bonded to the building Number board to form an integral heating panel. 2,138,217 JOHN F. SCHREIBER. 2,314,766 2,328,666

REFERENCES CITED 5 The fol lowing references are of record in the Number file of this patent: 224 648 UNITED STATES PATENTS 238,024 Number Name Date 10 427,255 1,891,595 Grierson Dec. 20, 1932 4691744 2,042,742 Taylor June 2, 1936 493,533

Name Date Sutter Nov. 29, 1938 Bull et a1 Mar. 23, 1943 Musgrave Sept. 7, 1943 FOREIGN PATENTS Country Date Great Britain Nov. 20, 1924 Great Britain Aug. 13, 1925 Great Britain Apr. 8, 1935 Great Britain July 30, 1947 Great Britain Jan. 4, 1937 

